VERX

VERTEX, INC._February 11, 2026 0001806837false00018068372026-02-112026-02-11 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): February 11, 2026

VERTEX, INC.

(Exact name of registrant as specified in its charter)

Delaware ​ ​ ​ 001-39413 ​ ​ ​ 23-2081753

(State or other jurisdiction of incorporation or organization)

(Commission File Number)

(I.R.S. Employer Identification No.)

​ 2301 Renaissance Blvd. King of Prussia, Pennsylvania 19406 (Address of principal executive offices) (Zip Code) (800) 355-3500 (Registrant’s telephone number, include area code) N/A (Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Securities registered pursuant to Section 12(b) of the Act: ​ Title of each class ​ ​ Trading Symbol(s) ​ ​ ​ Name of each exchange on which registered

Class A Common Stock, $0.001 par value per share ​

VERX

​ The Nasdaq Stock Market LLC

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). Emerging growth company ☐ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ ​ ​

Item 2.02. Results of Operations and Financial Condition. On February 11, 2026, Vertex, Inc. (the “Company”) issued a press release announcing its financial results for the fourth quarter and full year ended December 31, 2025. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. The information contained in this Item 2.02, including Exhibit 99.1 hereto, shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing made by the Company under the Securities Act of 1933, as amended, or the Exchange Act, regardless of any general incorporation language in such filings, unless expressly incorporated by specific reference in such filing. Item 9.01. Financial Statements and Exhibits. (d) Exhibits. The following exhibit relating to Item 2.02 shall be deemed to be furnished, and not filed: ​ Exhibit No. ​ ​ ​ Description

99.1

Press Release dated February 11, 2026

104 ​ Cover Page Interactive Data File (formatted as inline XBRL and contained in Exhibit 101)

​ ​ ​

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​

VERTEX, INC.

Date: February 11, 2026 By: /s/ Bryan Rowland

Name: Bryan Rowland

Title: General Counsel and Secretary

​ ​ ​ ​ ​ ​

VERTEX, INC._ October 30, 2025 0001806837false00018068372025-10-302025-10-30 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): October 30, 2025

VERTEX, INC.

(Exact name of registrant as specified in its charter)

Delaware

001-39413

23-2081753

(State or other jurisdiction of incorporation or organization)

(Commission File Number)

(I.R.S. Employer Identification No.)

​ 2301 Renaissance Blvd. King of Prussia, Pennsylvania 19406 (Address of principal executive offices) (Zip Code) (800) 355-3500 (Registrant’s telephone number, include area code) N/A (Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Securities registered pursuant to Section 12(b) of the Act: ​ Title of each class

Trading Symbol(s)

Name of each exchange on which registered

Class A Common Stock, $0.001 par value per share ​

VERX

​ The Nasdaq Stock Market LLC

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). Emerging growth company ☐ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ ​ ​

Item 2.02. Results of Operations and Financial Condition. On November 3, 2025, Vertex, Inc. (the “Company”) issued a press release announcing its financial results for the third quarter ended September 30, 2025 and the adoption of its first-ever stock repurchase program. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. The information contained in this Item 2.02, including Exhibit 99.1 hereto, shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing made by the Company under the Securities Act of 1933, as amended, or the Exchange Act, regardless of any general incorporation language in such filings, unless expressly incorporated by specific reference in such filing. Item 8.01. Other Events. On October 30, 2025, the Company’s Board of Directors authorized a stock repurchase program for up to $150 million of the Company's outstanding shares of Class A common stock (the “Repurchase Program”). Under the Repurchase Program, share repurchases may be made from time to time in one or more open market or privately negotiated transactions, and/or through other legally permissible means in accordance with applicable rules and regulations promulgated under the Exchange Act. The timing and amount of any shares repurchased will be determined by the Company's management based on its evaluation of market conditions and other factors. Repurchases may also be made under a Rule 10b5-1 plan, which would permit shares to be repurchased when the Company might otherwise be precluded from doing so under insider trading laws. Any repurchased shares will be available for use in connection with the Company’s stock plans and for other corporate purposes. The Repurchase Program has no termination date and may be modified, suspended or discontinued at any time. Item 9.01. Financial Statements and Exhibits. (d) Exhibits. The following exhibit relating to Item 2.02 and Item 8.01 shall be deemed to be furnished, and not filed: ​ Exhibit No.

Description

99.1

Press Release dated November 3, 2025

104 ​ Cover Page Interactive Data File (formatted as inline XBRL and contained in Exhibit 101)

​ ​ ​

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​

VERTEX, INC.

Date: November 3, 2025 By: /s/ Bryan Rowland

Name: Bryan Rowland

Title: General Counsel and Secretary

​ ​ ​ ​ ​ ​

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0001806837

2025-10-20 2025-10-20

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of report (Date of earliest event reported): October 20, 2025

VERTEX, INC.

(Exact name of registrant as specified in its charter)

Delaware

001-39413

23-2081753

(State or other jurisdiction

of incorporation or organization)

(Commission File Number)

(I.R.S. Employer

Identification No.)

2301 Renaissance Blvd.

King of Prussia, Pennsylvania 19406

(Address of principal executive offices) (Zip Code)

(800) 355-3500

(Registrant’s telephone number, include area code)

N/A

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

¨ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class

Trading Symbol(s)

Name of each exchange on which

registered

Class A common stock, $0.001 par value per share

VERX

The Nasdaq Stock Market LLC

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ¨

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

Item 2.02.         Results of Operations and Financial Condition.

On October 21, 2025, Vertex, Inc. (the “Company”) issued a press release announcing certain preliminary results for the three months ended September 30, 2025. A copy of the press release is furnished as Exhibit 99.1 hereto and is incorporated by reference herein.

Item 5.02          Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

On October 21, 2025, the Company announced that David DeStefano, the Company’s Chief Executive Officer, President and Chairperson of the board of directors of the Company (the “Board”), will retire as an executive officer of the Company effective as of November 10, 2025 (the “Retirement Date”). In connection with his retirement, Mr. DeStefano entered into a Retirement Agreement and Release with the Company (the “Retirement Agreement”), pursuant to which he will continue to advise the Company’s management team and perform such other services as may be reasonably requested from time to time by the Chief Executive Officer of the Company until December 31, 2025. The Company may extend the consulting period for additional one-month periods but not beyond March 31, 2026. Mr. DeStefano will remain as Chairperson of the Board. Pursuant to the Retirement Agreement, the Company will pay Mr. DeStefano a fee equal to $235,000 for the consulting services through December 31, 2025. If the Company extends the consulting period beyond December 31, 2025, the monthly fee will be equal to $50,000. Mr. DeStefano will remain eligible for his annual bonus for 2025, and his outstanding restricted stock units will continue to vest while he provides the consulting services and while he serves on the Board.

Mr. DeStefano executed a general release and waiver of claims against the Company. Mr. DeStefano continues to be bound by the confidentiality and restrictive covenant provisions set forth in his Executive Employment Agreement with the Company, dated July 6, 2020, which provides for non-competition and non-solicitation restrictions for two years following the Retirement Date and restrictions on the disclosure and use of confidential information at any time following the Retirement Date.

In connection with Mr. DeStefano’s retirement, the Board appointed Christopher Young as Chief Executive Officer, President and a Class III director of the Company effective as of November 10, 2025 (the “Commencement Date”). Prior to joining the Company, Mr. Young, age 53, served as Executive Vice President – Business Development, Strategy and Ventures of Microsoft Corp. from 2020-2025. He is currently a member of the board of directors for QUALCOMM Incorporated and American Express Company. From 2017 to 2020, he was the CEO of McAfee, LLC, one of the w